The present invention relates to a system and method wherein cargo, such as particulate material, like alumina, is pneumatically transported vertically from the hold of a ship, other vessel, or the like container; and after it has been transported vertically a distance, another section of the apparatus conveys the material or cargo generally horizontally to a collection point.
The present invention concerns an elevating and conveying system and a method for the unloading of materials, particularly particulate materials, from vessels, ships, or the like containers.
In this description, pneumatic transport means the conveying of particulate material solely by means of a high velocity moving gas which entrains the particles. This does not include a fluidized chute. In a vertical pipe, the moving gas alone lifts, entrains, carries and conveys the material. There are known pneumatic transport systems which employ a moving gas flow to suck cargo from a ship's hold, to elevate the cargo, and to blow the cargo through a direction changing bend in the pneumatic transport which bend may be at approximately 90.degree. or even at a greater angle. Following the bend, the cargo is blown by the same moving gas flow along a normally approximately horizontal or sloping path into a gas-particulate material separator. See U.S. Pat. No. 2,620,236, for example. Hence, pneumatic transport operates along the entire cargo or material transport pathway from the ship's hold, vessel, container or the like all the way to the remote gas-cargo separator. Such systems often transport particulate materials that have abrasive qualities and this damages the transport pipes, especially at the direction change bend.
Furthermore, along part of the pathway, such systems must convey the material along a more or less horizontal path. But, horizontal conveyance of particulates requires very high transport air velocities, for instance 25 meters per second or more, especially for heavy powders or other heavy particulate materials. Otherwise, the particulate materials settle at the bottom of the horizontal transport pipe and are not conveyed. With vertical transport, the air flow both supports and transfers the particles. But, with horizontal transport using a horizontal air flow, the air flow no longer supports the particles from beneath and a much greater air velocity is thus needed to effect horizontal transport. As a result, such known transport systems have their limits for reasons of both power consumption and excessive internal wear on the system.
One further drawback is that the capacity of these known systems is limited by considerations of the size and weight of the suction or moving gas flow line that can be used and the risk of clogging of the horizontal conveyor after change of direction due, for example, to pulsation in the horizontal transportation line.